Quantitative aspects of base-catalyzed Michael addition: Mechanistic study of structural and medium effects on rate

1969 ◽  
Vol 47 (11) ◽  
pp. 1965-1979 ◽  
Author(s):  
John A. Markisz ◽  
Joseph D. Gettler
Keyword(s):  
Experimental Data ◽  
Ionic Strength ◽  
Ionization Constants ◽  
Mechanistic Study ◽  
Basic Solution ◽  
Ionic Charge ◽  
Quantitative Correlation ◽  
System A ◽  
Kinetics Of ◽  
Good Agreement

The quantitative kinetics of the reactions of acrylonitrile and methyl vinyl ketone with ethyl acetoacetate and 2,4-pentanedione, and those of acrylonitrile with ethanol and methanol in basic solution were studied as functions of base concentration, temperature, ionic strength, and solvent composition. An expression is obtained which relates the observed rates to the basicity of the solution for the 2,4-pentanedione reactions by the amount of anion in solution. For the other systems, reasonable values of ionization constants obtained empirically, similarly correlate observed rates with the concentration of base in the system. A quantitative correlation with activity coefficients as expressed by the expanded form of the Debye–Hückel equation gave good agreement for most of the experimental data with ionic strength. A derivation for the particular type of system employed indicated that the activity coefficient for the double-bonded compounds appears to have to be treated as an ion with partial ionic charge. On the basis of experimental data reported, the mechanism proposed involves, (i) anion attack on a polarized double bond, (ii) formation of a cyclic intermediate, severely restricted because of π orbital overlap, and (iii) protonation of this intermediate to form product.

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

Kinetics and mechanistic study of the ruthenium(III) catalyzed oxidative deamination and decarboxylation of L-valine by alkaline permanganate

2001 ◽  
Vol 79 (12) ◽  
pp. 1926-1933 ◽  
Author(s):  
Dinesh C Bilehal ◽  
Raviraj M Kulkarni ◽  
Sharanappa T Nandibewoor
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Activation Parameters ◽  
Solvent Polarity ◽  
Mechanistic Study ◽  
Reaction Products ◽  
Order Dependence ◽  
Alkaline Permanganate ◽  
Kinetics Of ◽  
Catalyzed Oxidation

The kinetics of ruthenium(III) catalyzed oxidation of L-valine by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction between permanganate and L-valine in alkaline medium exhibits 2:1 stoichiometry (KMnO4:L-valine). The reaction shows first-order dependence on the concentration of permanganate and ruthenium(III) and less than unit-order dependence on the concentrations of L-valine and alkali. The reaction rate increases both with an increase in ionic strength and a decrease in solvent polarity of the medium. Initial addition of reaction products did not significantly affect the rate. A mechanism involving the formation of a complex between catalyst and substrate has been proposed. The activation parameters were computed with respect to the slowest step of the mechanism.Key words: oxidation, L-valine, catalysis, ruthenium(III), kinetics.

scholarly journals Thermodynamic modelling of the binary indium-lithium system, a promising li-ion battery material

2021 ◽  
pp. 41-41
Author(s):  
Wojciech Gierlotka ◽  
Władysław Gąsior ◽  
Adam Dębski ◽  
Miłosz Zabrocki
Keyword(s):  
Experimental Data ◽  
Ternary Systems ◽  
Calphad Approach ◽  
Li Ion Battery ◽  
System A ◽  
Proposed Model ◽  
Component Systems ◽  
Li Ion ◽  
Battery Material ◽  
Good Agreement

The binary In - Li system is a promising Li-ion battery anode material as well as a part of the important ternary Ge - In - Li system. The thermodynamic descriptions of metallic systems are widely used to retrieve information necessary for alloy applications. In this work, a thermodynamic model of a binary indium - lithium system prepared by the Calphad approach is proposed. The liquid phase was described by an associate model, and the solid phases determined by the ab-initio calculation were included in thermodynamic modeling. The obtained set of self-consistent thermodynamic parameters well reproduces the available experimental data and enables further calculations of multi-component systems. A good agreement between the calculations and the available experimental data was found. The proposed model can be used for further descriptions of ternary systems.

Kinetic Model of Thermoelastic Martensite Transformation in Niti and NiMn Based Shape Memory Alloys

1995 ◽  
Vol 398 ◽  
Author(s):  
K. H. Wu ◽  
J.D. Shi ◽  
F. Yang ◽  
Z. J. Pu
Keyword(s):  
Experimental Data ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensite Transformation ◽  
Quantitative Model ◽  
Proposed Model ◽  
Series Of Experiments ◽  
The Relationship ◽  
Kinetics Of ◽  
Good Agreement

ABSTRACTA new, quantitative model was developed to describe the martensite transformation kinetics of thermoelastic shape memory alloys (SMAs). In addition, a series of experiments were conducted to study the Kinetics of thermoelastic martensite transformation in four SMA systems: NiTi, NiTi-15at%Hf, NiTi-20at%Zr and NiMn-7.5at%Ti alloys. Comparisons between data of the kinetic of martensite transformation with the present theoretic models show that the proposed model is in good agreement and concurs with the experimental data. Also, a comparison of data from the proposed model with data from existing kinetic models, such as Liang's and Magee's [1,7], indicates that the proposed model can better describe the experimental data, including the relationship between dξ(T)/dT and ξ, and dξ(T)/dT and T.

DISPROPORTIONATION AND RECOMBINATION OF CYANISOPROPYL RADICALS: REARRANGEMENT OF DIMETHYLKETENECYANISOPROPYLIMINE TO TETRAMETHYLSUCCINODINITRILE

1959 ◽  
Vol 37 (7) ◽  
pp. 1165-1169 ◽  
Author(s):  
M. Talât-Erben ◽  
A. N. Isfendiyaroğlu
Keyword(s):  
Experimental Data ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Molecular Mechanism ◽  
Reaction Scheme ◽  
Side Reactions ◽  
Minor Importance ◽  
Azo Compound ◽  
Kinetics Of ◽  
Good Agreement

Evidence is presented that the ketenimine intermediate formed in the thermal decomposition of azo-bis-isobutyronitrile (AIBN) rearranges quantitatively to tetramethylsuccinodinitrile (TMSDN), mainly by a molecular mechanism. Interpretation of experimental data on the basis of a reaction scheme consistent with the nature of the main products and the features of the kinetics of the decomposition permits estimation, by means of a simple diagram, of the extent of disproportionation, as well as that of the normal and abnormal recombination of cyanisopropyl radicals. The result obtained for the latter is in good agreement with that determined previously by an alternative method. The analysis does not exclude absolutely the possibility of side reactions in which the azo-compound partly decomposes by a molecular process, and the intermediate decomposes into free radicals. However, it is concluded that these side reactions, if any, must be of minor importance.

An Approach for Analyzing the Growth Kinetics of Fe2B Phase on AISI 1018 Steel

2010 ◽  
Vol 297-301 ◽  
pp. 269-274 ◽  
Author(s):  
Mourad Keddam
Keyword(s):  
Experimental Data ◽  
Carbon Steel ◽  
Growth Kinetics ◽  
Boron Content ◽  
Kinetic Constant ◽  
Mass Gain ◽  
Iron Boride ◽  
Simulation Results ◽  
Kinetics Of ◽  
Good Agreement

A simulation of the growth kinetics of iron boride forming on AISI 1018 carbon steel was done on the basis of a kinetic model. This model including the effect of the incubation time during the formation of iron boride, was applied in order to evaluate the kinetic constant at the ( ) interface, the layer thickness and the mass gain depending on the paste-boriding parameters such as time, temperature and boron potential reflected by the corresponding value of the surface boron content. The simulation results were found to be in a good agreement with the experimental data derived from the literature.

THE KINETICS OF THE FORMATION OF THE MONOSULPHATO COMPLEX OF IRON (III) IN AQUEOUS SOLUTION

1962 ◽  
Vol 40 (9) ◽  
pp. 1836-1845 ◽  
Author(s):  
G. G. Davis ◽  
W. MacF. Smith
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Ionic Strength ◽  
Continuous Flow ◽  
Hydrogen Ions ◽  
Kcal Mole ◽  
Forward Reaction ◽  
First Order ◽  
Kinetics Of Formation ◽  
Kinetics Of

The kinetics of formation of the monosulphato complex of iron (III) has been examined spectrophotometrically using a continuous-flow technique over the range of temperatures 15.6 to 34.5 °C in an aqueous medium of ionic strength 0.5 and a range of concentrations of hydrogen ions 0.05 to 0.30 M. The experimental data may be interpreted on the assumption that the significant reactions are a bimolecular association opposed by a first-order dissociation [Formula: see text] For the forward reaction ΔH≠ is 18.0 kcal mole−1 and ΔS≠ is 19.4 cal mole−1 deg−1.

scholarly journals Further study on kinetic modeling of sunflower oil methanolysis catalyzed by calcium-based catalysts

2016 ◽  
Vol 22 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Marija Miladinovic ◽  
Marija Tasic ◽  
Olivera Stamenkovic ◽  
Vlada Veljkovic ◽  
Dejan Skala
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Kinetic Model ◽  
Sunflower Oil ◽  
Coefficient Of Determination ◽  
Reaction Conditions ◽  
High Coefficient ◽  
Relative Percentage ◽  
Kinetics Of ◽  
Good Agreement

The kinetic model, which was originally developed for sunflower oil methanolysis catalyzed by CaO.ZnO, was examined for several other calcium-based catalysts like neat CaO, quicklime and Ca(OH)2. This model including triacylglycerols mass transfer- and chemically-controlled regimes demonstrated a good agreement with the experimental data in terms of a high coefficient of determination (0.971?0.022) and acceptable mean relative percentage deviation (?15.9%). Hence, this model is recommended for modeling the kinetics of sunflower oil methanolysis over calcium-based catalysts under widely ranging reaction conditions.

scholarly journals Theoretical calculations of the kinetics of the OH reaction with 2-methyl-2-propen-1-ol and its alkene analogue

RSC Advances ◽  
2014 ◽  
Vol 4 (40) ◽  
pp. 20830-20840 ◽  
Author(s):  
Thaís da Silva Barbosa ◽  
Jorge D. Nieto ◽  
Pablo M. Cometto ◽  
Silvia I. Lane ◽  
Glauco Favilla Bauerfeldt ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Rate Coefficients ◽  
Kinetics Of ◽  
Good Agreement

The rate coefficients for the OH addition to 2-methyl-2-propen-1-ol and methylpropene have been determined, showing a non-Arrhenius profile and good agreement with the experimental data.

Kinetics of oxidation of nitrite by hypochlorite ions in aqueous basic solution

1976 ◽  
Vol 54 (21) ◽  
pp. 3401-3406 ◽  
Author(s):  
J. M. Cachaza ◽  
J. Casado ◽  
A. Castro ◽  
M. A. López Quintela
Keyword(s):  
Ionic Strength ◽  
Initial Step ◽  
Activation Energies ◽  
The Other ◽  
Basic Solution ◽  
Unimolecular Decomposition ◽  
Kinetics Of Oxidation ◽  
Rate Law ◽  
Kinetics Of

The kinetics of oxidation of nitrite to nitrate by hypochlorite ions in aqueous basic solution [Formula: see text] have been studied using a dynamic spectrophotometric technique. The rate law is[Formula: see text]At 298.0 K and ionic strength 0.40 M, d = (3.4 ± 0.2) × 10−8 mol l−1 s−1 and e = (2.8 ± 0.2) × 10−6 s−1. The associated activation energies are 56 ± 3 and 61 ± 3 kJ mol−1 respectively. A mechanism is proposed involving the reversible initial step:[Formula: see text]with the NO2Cl undergoing two parallel subsequent reactions, one a unimolecular decomposition and the other an attack by NO2− on NO2Cl.

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